Put at, in, on or - if no preposition is needed.

   -      at      in      on      on '—' is also possible   
1 A: 'What are you doing Easter?'
B: 'We haven't decided yet.'
2 It's traditional here to celebrate the first day of spring.
3 A woman sitting next to me dinner spilt her drink all over me.
4 Chan took power in a military coup the beginning of the decade.
5 She held the world record for seven years the 1970s.
6 his arrival in Thailand, Mr Surat fell ill and spent the next five weeks in hospital.
7 I was woken up the middle of the night by a helicopter going overhead.
8 I had to get up the night to close the window.
9 We meet every Saturday afternoon to go shopping.
10 He had to leave a quarter to six this morning to catch the train.
11 I'm afraid she's left now, but you'll be able to see her the day after tomorrow.
12 Don't worry, the exam will be over a couple of hours.
13 These pink roses have a beautiful smell which becomes stronger the evening.
14 The programme was shown on television one afternoon last week.
15 He painted the whole house only three days.